There seems to be some really good benefits for the animals but before I do it I want to make sure there won't be any adverse effects.
I don't thinks it's a question of whether or not the bowl itself is clean. Water naturally harbors bacteria. Whether you change waters every 3 days or once a week I imagine that would be enough time for bacteria to grow (I'm no scientist!) Especially in a room that's already kept humid. There also seems to be a lot of other health benefits linked to the copper in the water.